Constitutive modelling of the single chrystal superalloy CMSX-4 for industrial gas turbine applications

Single crystal superalloys are actively being considered for use in industrial gas turbines and it is therefore necessary to address the development of design assessment methodologies in parallel with the characterisation of candidate alloys. Current design practice, as applied to conventionally cast components, relies primarily on conventional design rules augmented by inelastic finite element analysis when the design rules are expected to be too restrictive. However, due to the anisotropy of the material response, the structural analogies used to support existing simplified methods are no longer applicable and inelastic Finite Element methods are considered as essential in the prediction of life of single crystal components. A number of activities of the single crystal Subgroup of Work Package 14 (COST 501) therefore concerned the development of material models which can be used to predict the anisotropic deformation behaviour of the commercially available alloy CIVISX-4 in the temperature range from 750øC to 950øC. The present paper examines a model based on a crystallographic slip formulation. The model was adjusted to uniaxial deformation data and verified by comparing with experimental data for multiaxial stress states. A newly developed software for parameter optimization with an interface to the finite element code ABAQUS was used.